1.A constraint perturbation method has been developed for finding optimal topology of a space truss subjected to asymmetric loads. The designs are traced with respect to the lower-bound cross-sectional areas. The method has been extended to find an optimal structural form of a braced plane frame.2.A method of generating sequences of seismic response constrained designs has been presented for trusses assembled to make large-span frames. The truss is subjected to a set of multi-component earthquake motions. Geometrical parameters are considered as design variables to find designs which satisfy the constraints on maximum response strains and accelerations.3.A new theory has been developed for generating a sequence of building frames with dampers such that the maximum interstory drifts under strong earthquakes exhibit almost uniform distribution. The designs are expanded with respect to a parameter representing the damping ratios of the viscous dampers.4.A straightforward method has been presented for shape design of cable networks with friction-free joints subjected to pretensioning forces. A design such that all the nodes exist in a plane is chosen as trivial initial design and a sequence of designs are expanded with respect to a boundary shape parameter.5.An inverse perturbation method has been developed for a base-isolated shear building model subjected to strong earthquakes. A sequence of designs is generated so that the maximum interstory drifts and top-floor acceleration are equal to the specified values.6.A design method has been developed for a shear building model supported by a pile-soil system. A sequence of stiffness designs are generated with respect to a ground stiffness parameter. This method utilizes a design for a stiff ground as an initial design and is applicable to the case where the fundamental natural period of the building and the ground are closely spaced and where the gound stiffness have estimation variability.